The long-term goal of this Bioengineering Research Partnerships is to develop semiconductor nanocrystals fluorescent probes (q- dots) technology that will provide biomedical research with better tools for diagnosis of diseases and biomedical techniques and instrumentation necessary for basic research of cellular and molecular structure and fundamental life processes. This includes q-dot probe synthesis, bio-conjugation techniques, dedicated optical instrumentation and unique imaging methodologies. We will develop optimized protocols for q-dot synthesis with desired optical, physical and chemical properties. Various spectroscopic and structural measurements will be used to fully characterize q-dots. This information will be fed back into the synthesis for optimization of the desired properties. Bio-conjugation schemes and labeling protocols will be developed for biomolecules and fixed and living cells. The utility and the new possibilities opened-up by q-dot technology will be demonstrated by studying protein trafficking and assembly in living cells and by physically mapping genes. The movements of secretory granule membranes during recycling will be tracked in living cells. Actin-based locomotion and mitotic spindle assembly will be imaged in real-time in cell- extracts. Molecular mechanism of synaptic transmitter release will be studied by following vesicle dynamics and protein trafficking in the synaptic apparatus. We will also physically map large number of distinct markers on chromosomes and combed DNA molecules and monitor the kinetics of chromosome pairing during meiotic prophase. All these demonstrations rely on the unique photophysical properties of q-dots, enabling new experiments and measurements to be performed and significant new biology to be revealed.